1. Field of the Invention
This invention relates to the continuous casting of metal tubing.
2. Prior Art
Heretofore metal tubing has been cast or proposed for casting by a variety of techniques. My U.S. Pat. No. 3,680,624, Woodburn, Jr. U.S. Pat. No. 3,410,333, Tarmann U.S. Pat. No. 3,346,036, and Byrnes U.S. Pat. No. 750,253 are believed to be representative of the prior art.
In my aforementioned U.S. Pat. No. 3,680,624 a closed-end mold is utilized in a process of continuously casting metal tubing. The process includes forming a solidified shell of a tube about a molten core in contact therewith, molten metal from the source flowing through the shell toward the mold during separation of the mold and the source. The source includes a starting bar, and on termination of the flow from the source continuing relative separation of the source and the mold utilizes the molten metal in the shell as a source to form additional solidified shell as the level of the source in the shell drops, leaving behind it a hollow tube while the source in the shell diminishes. In Woodburn, Jr. U.S. Pat. No. 3,410,333 a pressurized source of molten metal is utilized to flow metal upwardly in a tube into a mold from which a casting in the form of a tube is drawn.
The aforementioned Tarmann U.S. Pat. No. 3,346,036 discloses casting tubing in which molten metal is poured in the top of an open-ended mold for continuous casting and a partially solidified casting is withdrawn from the mold and guided along an initially descending and then ascending, curved path to a level in which the liquid part of the casting cannot rise further so that the liquid metal inside the casting rises only to the pouring level. The tube is drawn off above this level from this curved portion of the casting.
Byrnes, U.S. Pat. No. 750,253 discloses a technique of casting a tubular article employing a mandrel for shaping the solidifying casting therearound as the casting is drawn off the mandrel. The mandrel is located centrally with reference to chilling and forming mold and has reciprocating movement with respect thereto and with reference to the source of molten metal for the supply of molten metal to the mold.
The present invention overcomes the difficulties associated with the prior art techniques and apparatus described above.